Pressure sensitive inks are well known for use in a variety of applications where it is desirable to obtain various electrical outputs in response to varying pressure or force applied across a layer or laminate of the ink, and in particular for use in various tactile or pressure sensitive devices of the type described in U.S. Pat. Nos. 4,856,993, 4,734,034 and 5,033,291. Such devices are capable of creating electrical signals with a monotony dependent upon applied mechanical pressure or force. Such devices include pressure transducers, sensors, strain gauges and the like.
Prior art inks sometimes have difficulties in applications in pressure sensitive devices due to limitations on one or more of hysteresis characteristics, sensitivity, temperature stability, difficulty in manufacturing and lack of consistency and accuracy in general electromechanical properties. For example, temperature limitations can affect the ability of certain inks to be useful in certain pressure transducers. Many current inks are often capable of operation of temperatures only up to approximately 100.degree. F.; however, there are applications where stability at temperatures in excess of 1000.degree. F. is desirable or required.
Printed circuits, switches and the like often incorporate electrically conductive inks useful as conductors or resistors where pressure sensitive properties, i.e., variation in resistivity with applied pressure variation, is not identified or used. Some such devices may incorporate nanoparticle semiconductive material in elastic components to achieve conductivity.